Add javac plugin for detecting common error cases at compile time (#8196)

Adds a `@NoDiscard` annotation that can be placed on methods to guarantee their return values are used and on types to guarantee that any method returning that type uses the return value.

Methods that call `@NoDiscard`-annotated functions can add a `@SuppressWarnings("NoDiscard")` or `@SuppressWarnings("all")` annotation (or annotation on the class declaring that method) to silence the compiler error warnings.

CMakeLists.txt

@@ -289,6 +289,7 @@ endif()
 set(FILENAME_DEP_REPLACE "get_filename_component(SELF_DIR \"$\{CMAKE_CURRENT_LIST_FILE\}\" PATH)")
 set(SELF_DIR "$\{SELF_DIR\}")
 set(WPIUNITS_DEP_REPLACE_IMPL "find_dependency(wpiunits)")
+set(WPIANNOTATIONS_DEP_REPLACE_IMPL "find_dependency(wpiannotations)")
 set(WPIUTIL_DEP_REPLACE "find_dependency(wpiutil)")
 add_subdirectory(wpiutil)
 
@@ -308,6 +309,10 @@ if(WITH_WPIMATH)
     add_subdirectory(wpimath)
 endif()
 
+if(WITH_JAVA)
+    add_subdirectory(wpiannotations)
+endif()
+
 if(WITH_WPIUNITS AND NOT WITH_WPIMATH)
     # In case of building wpiunits standalone
     set(WPIUNITS_DEP_REPLACE ${WPIUNITS_DEP_REPLACE_IMPL})